The invention relates to a cylinder head gasket, and, in particular, to an at least substantially metallic cylinder head gasket, for influencing the flow of coolant within a reciprocating internal combustion engine comprising several combustion chambers arranged one after another (this can be a so-called in-line engine, or equally well a so-called V-engine or any other engine having several so-called cylinder banks).
A conventional flow of coolant through such an engine will first be explained with reference to an in-line engine, however, the same applies accordingly to other engines with several cylinder banks. The coolant is mostly introduced into the engine block (often also referred to as cylinder block or crankcase) at a narrow or end face of the engine by the coolant pump of the engine such that the direction of the flow of coolant at the point of introduction is oriented in the longitudinal direction of the engine, i.e., in the direction of the row of cylinders. The coolant then essentially flows past the row of cylinders into the area of the other narrow or end face of the engine. In this area, the cylinder head gasket clamped between engine block and cylinder head has coolant passage openings through which the coolant is conducted into the cylinder head—since the coolant pump of the engine is arranged upstream of the engine block a higher coolant pressure prevails in the coolant cavities of the engine block than in the cylinder head. The coolant is conducted away at the cylinder head, namely in the area of that end face of the engine at which the flow of coolant is introduced into the engine block. When the cylinder head, which in a plan view corresponds approximately to a narrow rectangle, is considered, the intake ports are located at one longitudinal side thereof, and the exhaust ports at the other opposite longitudinal side thereof. In order to achieve better and more uniform cooling, above all, of the cylinder head, cylinder head gaskets have also been used, which comprise coolant passage openings not only in the area of one end face of the engine but also in the areas of the two longitudinal sides of the engine, with the coolant passage openings neighboring on the exhaust gas side of the cylinder head being larger than the coolant passage openings of the cylinder head gasket neighboring on the intake side of the cylinder head in order that the exhaust gas side of the cylinder head will be cooled better. In any case, such a flow of coolant prevails in the engine that in the vicinity of the cylinder head gasket both in the engine block and in the cylinder head a main flow component of the flow of coolant runs approximately parallel to the plane defined by the cylinder head gasket or its gasket plate (either in longitudinal direction of the engine or approximately diagonally from an edge of one narrow side to the diagonally opposite edge of the other narrow side, and the latter in the case where the cylinder head gasket has larger coolant passage openings on the exhaust gas side than on the intake side).
The flow conditions explained hereinabove result in zones in the cylinder head of known engines which are insufficiently cooled by the coolant. The inventors have found that this is also due to the following circumstance: In the hitherto conventional cylinder head gaskets the coolant passage openings thereof have been in the form of simple holes; furthermore, the gasket plates of the cylinder head gaskets are relatively thin, above all, since in many cases single-layered or multilayered metallic gaskets have replaced the old, somewhat thicker so-called soft-material gaskets (at least in substantially metallic cylinder head gaskets the thickness of the gasket plate is between 0.25 and 2.0 mm). Therefore, those partial flows of the coolant which flow through the coolant passage openings of the gasket plate from the engine block into the cylinder head do not form any distinctively oriented coolant flows of considerable kinetic energy, with the result that in the coolant cavity or coolant cavities of the cylinder head the flow of coolant predominantly directed approximately parallel to the cylinder head gasket above the coolant passage openings of the gasket cannot be deflected to any great extent by these partial flows of coolant. In order to avoid local overheating in the cylinder head caused by dead zones in the flow of coolant, particularly sophisticated configurations of the cylinder head in terms of casting technology have therefore hitherto proven necessary.
The object underlying the invention is to create a cylinder head gasket with which the problems explained hereinabove can at least be mitigated, if not completely eliminated.